First-line pharmacotherapy for dystonia is which agent?

• A. Benztropine
• B. Haloperidol
• C. Fluoxetine
• D. Valproate

Answer: (A)

Dystonia treatment aims to rebalance the cholinergic and dopaminergic signaling in the basal ganglia. Benztropine is a central anticholinergic that blocks muscarinic receptors, reducing acetylcholine activity in the striatum. This helps restore balance with dopamine and typically lowers the involuntary muscle contractions and abnormal postures seen in dystonia. Because of this mechanism, benztropine is the standard first-line systemic pharmacotherapy for dystonia, especially in younger patients or generalized forms. In focal dystonias, localized treatments like botulinum toxin injections are also very effective, but for a systemic medication option, benztropine is the go-to. Other options listed do not address the underlying motor circuitry in the same way: haloperidol can worsen dystonia through dopamine blockade and extrapyramidal symptoms, while fluoxetine and valproate are not treatments for dystonia. Side effects of benztropine, such as dry mouth, constipation, urinary retention, and potential cognitive effects, should be considered, particularly in older patients.